"Expand the milling capabilities of your LumberPro HD36 sawmill with this 4-ft.L bed extension. By itself, the HD36 can mill 13-ft. long logs. With one extension that becomes 17ft. With two, it's 21. With seven, you can mill 41-ft. long logs. There's no limit to what you can do. Each 4-foot extension bolts permanently to the end of the log deck. Made with twin double-plated debossed galvanized steel. Compatible with Item#s 190618 and 190619. Rail Material Steel, Dimensions L x W x H in. 48 x 45 x 10, Rails in. 48, Cross Bunks in. 41 bottom, 29 top x 11 7/8, Works With LumberPro HD36 sawmill, Application Bed extension, Cross Bunk Material Steel."